Press Releases

Arena Pharmaceuticals Offers to Purchase Three Million Shares Owned By Its Largest Stockholder at 90% of Market Value And Amends Stockholders Agreement With the Stockholder

SAN DIEGO, Oct 8, 2003 /PRNewswire-FirstCall via COMTEX/ -- Arena Pharmaceuticals, Inc.
(Nasdaq: ARNA) today announced that the Stockholders Agreement dated as of
January 17, 2003, with its largest stockholder, Biotechnology Value Fund, L.P.
and certain related entities ("BVF"), has been amended, and that the parties
are in discussions about possibly further amending the agreement.

Arena has two offer rights under the Stockholders Agreement. Pursuant to
the initial right, Arena can offer to purchase at least three million shares
of Arena common stock from BVF at a cash purchase price per share representing
a ten percent (10%) discount to Market Value (as defined in the Stockholders
Agreement). As amended, the Stockholders Agreement provides that BVF can
accept or reject this initial offer by the earlier of ten days following the
notice of the offer or two business days after Arena requests a response (the
Stockholders Agreement previously provided that BVF had two business days to
respond). If BVF rejects the offer, Arena then has the right during the next
ten business day period to make a second offer to purchase at least three
million shares of Arena common stock from BVF at a price that is higher than
the price offered in the first offer. If BVF accepts either the initial offer
or the second offer, or if the second offer is $8.00 or more per share, the
standstill under the Stockholders Agreement would be extended until
December 31, 2004.

In order to protect Arena's rights under the Stockholders Agreement while
discussions about possibly further amending the agreement are ongoing, Arena
made the initial offer on October 7, 2003, at a price of $7.69 per share. The
Market Value on October 7, 2003, was $8.54, which was the closing price of
Arena's common stock on the Nasdaq Stock Market® on that day. There is no
assurance as to whether BVF will accept the initial offer, whether Arena will
make the second offer or whether the current discussions between Arena and BVF
will result in a further amendment to the Stockholders Agreement.

The Stockholders Agreement is filed as Exhibit 10 to Arena's
January 21, 2003, Form 8-K.

Arena is a biopharmaceutical company focused on discovering and developing
drugs that act on an important class of drug targets called G protein-coupled
receptors, or GPCRs. Arena uses its Constitutively Activated Receptor
Technology, or CART, Melanophore technology and other proprietary
technologies to better understand GPCRs and to identify small molecules that
may lead to new drugs. Arena focuses its efforts in four therapeutic areas:
metabolic diseases, cardiovascular diseases, central nervous system disorders
and inflammatory diseases. Within these areas, Arena is developing a
portfolio of internally discovered, highly selective small molecules for large
markets with unmet medical needs, including obesity, diabetes, depression and
sleep disorders.

Certain statements in this press release are forward-looking statements
that involve a number of risks and uncertainties. Such forward-looking
statements include statements about further discussions with BVF, a possible
future amendment to the Stockholders Agreement, Arena's strategy,
technologies, internal programs, future achievements, and statements that are
not historical facts, including statements about our ability to identify and
develop small molecules or which are preceded by the word "will" or similar
words. For such statements, Arena claims the protection of the Private
Securities Litigation Reform Act of 1995. Actual events or results may differ
materially from Arena's expectations. Important factors that could cause
actual results to differ materially from those stated or implied by Arena's
forward-looking statements are disclosed in Arena's SEC reports, including
Arena's most recent quarterly report on Form 10-Q. These forward-looking
statements represent Arena's judgment as of the date of this release. Arena
disclaims any intent or obligation to update these forward-looking statements.

Arena Pharmaceuticals® and Arena® are registered service marks of the
company. CART is an unregistered service mark of the company. Arena's
headquarters are at 6166 Nancy Ridge Drive, San Diego, California 92121, and
its telephone number is (858) 453-7200. On the Internet, please refer to
Arena's Web site at www.arenapharm.com for further information.